<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>

</head>

<body>
    <div id="root">
        <h2>今天天气{{info}}</h2>
        <button @click="change">切换天气</button>

    </div>
    <script src="../vue.js"></script>
    <script>
        Vue.config.productionTip = false
        const vm = new Vue({
            el: "#root",
            data: {
                isHot: true,
            },
            computed:
            {
                info() {
                    return this.isHot ? '炎热' : '凉爽'
                }
            },
            methods:
            {
                change() {
                    this.isHot = !this.isHot
                }
            },
            watch: {
                //正常写法
                isHot: {
                    handler(newValue, oldValue) {
                        console.log('isHot发生修改', newValue, oldValue);
                    }
                },
                //简写模式  没有配置项的时候
                isHot(newValue, oldValue)
                {
                    console.log('isHot发生修改', newValue, oldValue);
                }
            },

        })

    </script>
</body>

</html>